These studies are directed toward understanding processing of visual information in the retina by recording intracellularly from each type of retinal cell in salamanders, toads and turtles. We are looking at the properties of lateral interactions at each plexiform layer and their effects upon retinal ganglion cell function, and we are studying the subsynaptic events through which these functions are mediated. We propose to characterize the properties of lateral interactions at the two retinal plexiform layers in an effort to establish a quantitative framework in which to describe the response of bipolar and ganglion cells, so that these studies can be related to retinal activity in higher vertebrates. From these studies we hope to be able to predict the form of the retinal output in response to any configuration of illumination, to determine the synaptic pathways which mediate lateral interactions in the retina, and to establish a framework in which to look at the subsynaptic events mediating the interactions. We are concurrently looking at the subsynaptic mechanisms with special tools which allow us to characterize the electrical events underlying synaptic activity at each retinal level. These studies will allow us to describe the properties of transmitter release, determine the nature of synaptic transmitters in the retina, and to characterize the changes in postsynaptic membranes associated with synaptic transmission. BIBLIOGRAPHIC REFERENCES: Werblin, F.S. (1975) "Regenerative Hyperpolarization in Rods," J. Physiol. 244, 53-81. Werblin, F.S. (1975) "Anomalous Rectification in Horizontal Cells," J. Physiol. 244, 639-657.